Method, apparatus, and system for forwarding packet in service function chaining sfc

ABSTRACT

The disclosure application discloses a method. The method includes: determining, by a control node, routing entry information of a service function forwarding node in a SFP in the SFC, where the routing entry information records a mapping relationship between route prefix information and next hop information, the route prefix information includes a SPI and a SI, the SPI is used to identify the SFP, the SI is used to identify a location of the service function forwarding node in the SFP, and the next hop information is used to indicate a next hop node of the service function forwarding node in the SFP; and sending, by the control node, the routing entry information to the service function forwarding node, where the routing entry information is used by the service function forwarding node to generate a forwarding table used to instruct the service function forwarding node to forward a packet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2016/088246, filed on Jul. 1, 2016, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present application relate to the communicationsfield, and to a method, an apparatus, and a system for forwarding apacket in service function chaining (SFC).

BACKGROUND

Service function chaining (SFC) is a mechanism for deploying avalue-added service. In network communications, the SFC is formed bycombining a group of devices that have service processing functions (forexample, a firewall (firewall), network address translation (NAT), anddeep packet inspection (DPI)) in an orderly manner, and allowing trafficto pass through these service functions. A basic architecture of the SFCincludes a control node, a classification node, a service functionforwarding node, a service function node, and the like.

An SFC service is deployed in software-defined networking (SDN). The SDNincludes a controller (which is an example of the control node) and anSDN routing and switching device (which is an example of the servicefunction forwarding node). The controller and the SDN routing andswitching device deliver a forwarding entry (for example, a flow table)in a point-to-point manner by using a southbound interface protocol, forexample, OpenFlow. This service function forwarding node is an SDN-onlyrouting and switching device that supports only an operation defined bythe OpenFlow specification.

However, in an existing SDN, a mainstream SDN routing and switchingdevice is an SDN hybrid routing and switching device, for example, anOpenFlow-hybrid switch. This SDN hybrid routing and switching device isusually implemented based on hardware improvements of a conventionalrouting and switching device. The hardware improvements for theconventional routing and switching device that are made by vendors areprivate extensions, and the private extensions of the vendors are notunified. Consequently, interaction between the conventional routing andswitching device and the controller cannot be standardized, andinterconnection of an SFC service between the controller and the routingand switching device is difficult to implement.

SUMMARY

The present application provides a method, an apparatus, and a systemfor forwarding a packet in service function chaining (SFC). Interactionbetween a routing and switching device and a controller is standardized,to implement smooth interconnection of an SFC service between thecontroller and the routing and switching device.

According to a first aspect, the present application provides a methodfor forwarding a packet in SFC, where the method includes: determining,by a control node, routing entry information of a service functionforwarding node in a service function path (SFP) in the SFC, where therouting entry information records a mapping relationship between routeprefix information and next hop information, the route prefixinformation includes a service path identifier (SPI) and a service index(SI), the SPI is used to identify the SFP, the SI is used to identify alocation of the service function forwarding node in the SFP, and thenext hop information is used to indicate a next hop node of the servicefunction forwarding node; and sending, by the control node, the routingentry information to the service function forwarding node, where therouting entry information is used by the service function forwardingnode to generate a forwarding table, and the forwarding table is used toinstruct the service function forwarding node to forward a packet.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers the routing entry information to the service functionforwarding node, the service function forwarding node generates theforwarding table, and interaction between the control node and theservice function forwarding node is standardized by using a matureprotocol, to implement smooth interconnection of an SFC service betweenthe control node and the service function forwarding node.

Further, the SPI and the SI are used as routes in a conventional routingand switching device to direct the packet. To be specific, a routingpolicy that exists in an existing SDN device is used to flexibly processthe routes that exist in a “SPI and SI” manner. Compared with anexisting conventional routing and switching device, the routing andswitching device in the present application is more convenient andflexible.

With reference to the first aspect, in a first possible implementationof the first aspect, the sending, by the control node, the routing entryinformation to the service function forwarding node includes:generating, by the control node, a Border Gateway Protocol (BGP) updatepacket, where the BGP update packet carries the routing entryinformation; and sending, by the control node, the BGP update packet tothe service function forwarding node.

With reference to the first aspect and the foregoing possibleimplementation, in a second possible implementation of the first aspect,the generating, by the control node, a BGP update packet, where the BGPupdate packet carries the routing entry information includes:generating, by the control node, the BGP update packet, where the BGPupdate packet includes a multiprotocol reachable network layerreachability information (MP_REACH_NLRI) attribute field, theMP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield, the SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, the NLRI field includes atype-length-value (TLV) field, a type T field of the TLV field indicatesthat a type of the TLV field is an SFC routing entry synchronizationtype, a value V field of the TLV field carries the SPI and the SI, andthe next hop information field carries the next hop information.

An extension is performed based on an existing BGP protocol. To bespecific, an NLRI field in a BGP Flow Spec packet carries match iteminformation, and a redirected extended community attribute field in theBGP Flow Spec packet carries to-be-executed action domain information.

With reference to the first aspect and the foregoing possibleimplementations, in a third possible implementation of the first aspect,the routing entry information further includes route attributeinformation, and the route attribute information includes at least oneof the following traffic distribution parameter types: weight, cost, andbandwidth, where the BGP update packet further includes a BGP SFCattribute field, the BGP SFC attribute field includes at least onesub-TLV field, and each traffic distribution parameter type correspondsto one of the at least one sub-TLV field. Each sub-TLV field includes aT field, an L field, and a V field, where the T field indicates any oneof the traffic distribution parameter types, and the V field indicates aparameter used to distribute, based on a corresponding trafficdistribution parameter type, traffic carried by the packet.

The route attribute information is carried in the routing entryinformation, and the service function forwarding node can distributetraffic based on the traffic distribution parameters included in theroute attribute information, so that traffic is distributed moreproperly and flexibly in the SFC.

According to a second aspect, the present application provides a methodfor forwarding a packet in SFC, where the method includes: receiving, bya service function forwarding node, routing entry information sent by acontrol node, where the routing entry information records a mappingrelationship between route prefix information and next hop information,the route prefix information includes a service path identifier (SPI)and a service index (SI), the SPI is used to identify an SFP, the SI isused to identify a location of the service function forwarding node inthe SFP, and the next hop information is used to indicate a next hopnode of the service function forwarding node; and storing, by theservice function forwarding node, the routing entry information into arouting table of the service function forwarding node, so that theservice function forwarding node generates a forwarding table based onthe routing table, and forwards a packet based on the forwarding table.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers the routing entry information to the service functionforwarding node, the service function forwarding node generates theforwarding table, and interaction between the control node and theservice function forwarding node is standardized by using a matureprotocol, to implement smooth interconnection of an SFC service betweenthe control node and the service function forwarding node.

Further, the SPI and the SI are used as routes in a conventional routingand switching device to direct the packet. To be specific, a routingpolicy that exists in an existing SDN device is used to flexibly processthe routes that exist in a “SPI and SI” manner. Compared with anexisting conventional routing and switching device, the routing andswitching device in the present application is more convenient andflexible.

With reference to the second aspect, in a first possible implementationof the second aspect, the receiving, by a service function forwardingnode, routing entry information sent by a control node includes:receiving, by the service function forwarding node, a Border GatewayProtocol (BGP) update packet sent by the control node, where the BGPupdate packet carries the routing entry information.

Further, the BGP update packet includes a multiprotocol reachablenetwork layer reachability information (MP_REACH_NLRI) attribute field,the MP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield, the SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, the NLRI field includes atype-length-value (TLV) field, a type T field of the TLV field indicatesthat a type of the TLV field is an SFC routing entry synchronizationtype, a value V field of the TLV field carries the SPI and the SI, andthe next hop information field carries the next hop information.

With reference to the second aspect and the foregoing possibleimplementation, in a second possible implementation of the secondaspect, the routing entry information further includes route attributeinformation, and the route attribute information includes at least oneof the following traffic distribution parameter types: weight, cost, andbandwidth, where the BGP update packet further includes a BGP SFCattribute field, the BGP SFC attribute field includes at least onesub-TLV field, and each traffic distribution parameter type correspondsto one of the at least one sub-TLV field. Each sub-TLV field includes aT field, an L field, and a V field, where the T field indicates any oneof the traffic distribution parameter types, and the V field indicates aparameter used to distribute, based on a corresponding trafficdistribution parameter type, traffic carried by the packet.

The route attribute information is carried in the routing entryinformation, and the service function forwarding node can distributetraffic based on the traffic distribution parameters included in theroute attribute information, so that traffic is distributed moreproperly and flexibly in the SFC.

With reference to the second aspect and the foregoing possibleimplementations, in a third possible implementation of the secondaspect, the storing, by the service function forwarding node, therouting entry information into a routing table of the service functionforwarding node includes: searching, by the service function forwardingnode based on the SPI and the SI, the routing table of the servicefunction forwarding node for target routing entry information having thesame SPI and SI; and updating, by the service function forwarding node,the target routing entry information based on the routing entryinformation when the target routing entry information is found; orstoring, by the service function forwarding node, the routing entryinformation when the target routing entry information is not found.

By synchronization of the routing table with the control node, therouting table stored in the service function forwarding node can beupdated in real time based on a change of a network, so that the servicefunction forwarding node determines an optimal path based on a networkstatus, generates the forwarding table, and forwards the packet based onthe forwarding table.

According to a third aspect, the present application provides a methodfor forwarding a packet in SFC, where the method includes: determining,by a control node, forwarding entry information of a service functionforwarding node in a service function path (SFP) in the SFC, where theforwarding entry information records a mapping relationship betweenforwarding prefix information and next hop information, the forwardingprefix information includes a service path identifier (SPI) and aservice index (SI), the SPI is used to identify the SFP, the SI is usedto identify a location of the service function forwarding node in theSFP, and the next hop information is used to indicate a next hop node ofthe service function forwarding node; generating, by the control node, aBorder Gateway Protocol (BGP) packet, where the BGP packet carries theforwarding entry information; and sending, by the control node, the BGPpacket to the service function forwarding node, where the forwardingentry information carried by the BGP packet is used to instruct theservice function forwarding node to forward a packet.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers the forwarding entry information to the service functionforwarding node by using the BGP packet, and the service functionforwarding node can directly forward the packet based on the forwardingentry information. Interaction between the control node and the servicefunction forwarding node is standardized by using a mature protocol, toimplement smooth interconnection of an SFC service between the controlnode and the service function forwarding node.

Further, a control plane is separated from a forwarding plane, so thatcontrol planes of forwarding nodes are centralized on the controller,which helps to implement a centralized service deployment strategy andimplement a centralized management and maintenance strategy.

With reference to the third aspect, in a first possible implementationof the third aspect, the generating, by the control node, a BorderGateway Protocol (BGP) packet, where the BGP packet carries theforwarding entry information includes: generating, by the control node,the BGP packet, where the BGP packet includes a multiprotocol reachablenetwork layer reachability information (MP_REACH_NLRI) attribute fieldthat is encapsulated based on an encapsulation format supported by anSFC synchronization address family, the MP_REACH_NLRI attribute fieldincludes an NLRI field and a next hop information field, the NLRI fieldincludes a type-length-value (TLV) field, a type T field of the TLVfield indicates that a type of the TLV field is a forwarding entrysynchronization type, a value V field of the TLV field carries the SPIand the SI, and the next hop information field carries the next hopinformation.

An extension is performed based on an existing BGP protocol. To bespecific, an NLRI field in a BGP Flow Spec packet carries match iteminformation, and a redirected extended community attribute field in theBGP Flow Spec packet carries to-be-executed action domain information.

With reference to the third aspect and the foregoing possibleimplementation of the third aspect, in a second possible implementationof the third aspect, the forwarding entry information includesforwarding attribute information, and the forwarding attributeinformation includes at least one of the following traffic distributionparameter types: weight, cost, and bandwidth, where the BGP packetincludes a BGP SFC attribute field, the BGP SFC attribute field includesat least one sub-TLV field, and each traffic distribution parameter typecorresponds to one of the at least one sub-TLV field. Each sub-TLV fieldincludes a T field, a L field, and a V field, where the T fieldindicates any one of the traffic distribution parameter types, and the Vfield indicates a parameter used to distribute, based on a correspondingtraffic distribution parameter type, traffic carried by the packet.

The route attribute information is carried in the forwarding entryinformation, and the service function forwarding node can distributetraffic based on the traffic distribution parameters included in theroute attribute information, so that traffic is distributed moreproperly and flexibly in the SFC.

Optionally, the BGP packet is a BGP update packet.

According to a fourth aspect, the present application provides a methodfor forwarding a packet in SFC, where the method includes: receiving, bya service function forwarding node, a Border Gateway Protocol BGP packetsent by a control node, where the BGP packet carries forwarding entryinformation, the forwarding entry information records a mappingrelationship between forwarding prefix information and next hopinformation, the forwarding prefix information includes a service pathidentifier (SPI) and a service index (SI), the SPI is used to identifyan SFP, the SI is used to identify a location of the service functionforwarding node in the SFP, and the next hop information is used toindicate a next hop node of the service function forwarding node; andstoring, by the service function forwarding node, the forwarding entryinformation, so as to forward a packet based on the forwarding entryinformation.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers the forwarding entry information to the service functionforwarding node by using the BGP packet, and the service functionforwarding node can directly forward the packet based on the forwardingentry information. Interaction between the control node and the servicefunction forwarding node is standardized by using a mature protocol, toimplement smooth interconnection of an SFC service between the controlnode and the service function forwarding node.

Further, a control plane is separated from a forwarding plane, so thatcontrol planes of forwarding nodes are centralized on the controller,which helps to implement a centralized service deployment strategy andimplement a centralized management and maintenance strategy.

With reference to the fourth aspect, in a first possible implementationof the fourth aspect, the BGP packet includes a multiprotocol reachablenetwork layer reachability information (MP_REACH_NLRI) attribute field,the MP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield, the SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, the NLRI field includes atype-length-value (TLV) field, a type T field of the TLV field indicatesthat a type of the TLV field is an SFC forwarding entry synchronizationtype, a value V field of the TLV field carries the SPI and the SI, andthe next hop information field carries the next hop information.

An extension is performed based on an existing BGP protocol. To bespecific, an NLRI field in a BGP Flow Spec packet carries match iteminformation, and a redirected extended community attribute field in theBGP Flow Spec packet carries to-be-executed action domain information.

With reference to the fourth aspect and the foregoing possibleimplementation of the fourth aspect, in a second possible implementationof the fourth aspect, the forwarding entry information includesforwarding attribute information, and the forwarding attributeinformation includes at least one of the following traffic distributionparameter types: weight, cost, and bandwidth, where the BGP packetincludes a BGP SFC attribute field, the BGP SFC attribute field includesat least one sub-TLV field, and each traffic distribution parameter typecorresponds to one of the at least one sub-TLV field. Each sub-TLV fieldincludes a T field, a L field, and a V field, where the T fieldindicates any one of the traffic distribution parameter types, and the Vfield indicates a parameter used to distribute, based on a correspondingtraffic distribution parameter type, traffic carried by the packet.

The forwarding attribute information is carried in the forwarding entryinformation, and the service function forwarding node can distributetraffic based on the traffic distribution parameters included in theforwarding attribute information, so that traffic is distributed moreproperly and flexibly in the SFC.

With reference to the fourth aspect and the foregoing possibleimplementations of the fourth aspect, in a third possible implementationof the fourth aspect, the storing, by the service function forwardingnode, the forwarding entry information includes: searching, by theservice function forwarding node based on the SPI and the SI, aforwarding table of the service function forwarding node for targetforwarding entry information having the same SPI and SI; and updating,by the service function forwarding node, the target forwarding entryinformation based on the forwarding entry information when the targetforwarding entry information is found; or storing, by the servicefunction forwarding node, the forwarding entry information when thetarget forwarding entry information is not found.

By synchronization of the forwarding table with the control node, theforwarding table stored in the service function forwarding node can beupdated in real time based on a change of a network, so as to directlyforward, when a packet with same traffic characteristic information isreceived subsequently, the packet based on the forwarding entryinformation.

Optionally, the BGP packet is a BGP update packet.

According to a fifth aspect, the present application provides a controlnode, configured to perform the method according to the first aspect orany possible implementation of the first aspect. The control nodeincludes a module configured to perform the method according to thefirst aspect or any possible implementation of the first aspect.

According to a sixth aspect, the present application provides a servicefunction forwarding node, configured to perform the method according tothe second aspect or any possible implementation of the second aspect.The service function forwarding node includes a module configured toperform the method according to the second aspect or any possibleimplementation of the second aspect.

According to a seventh aspect, the present application provides a systemfor forwarding a packet in SFC, including the control node provided inthe fifth aspect and the service function forwarding node provided inthe sixth aspect.

According to an eighth aspect, the present application provides acontrol node, configured to perform the method according to the thirdaspect or any possible implementation of the third aspect. The controlnode includes a module configured to perform the method according to thethird aspect or any possible implementation of the third aspect.

According to a ninth aspect, the present application provides a servicefunction forwarding node, configured to perform the method according tothe fourth aspect or any possible implementation of the fourth aspect.The service function forwarding node includes a module configured toperform the method according to the fourth aspect or any possibleimplementation of the fourth aspect.

According to a tenth aspect, the present application provides a systemfor forwarding a packet in SFC, including the control node provided inthe eighth aspect and the service function forwarding node provided inthe ninth aspect.

According to an eleventh aspect, the present application provides acontrol node, where the control node includes a receiver, a transmitter,a memory, a processor, and a bus system. The receiver, the transmitter,the memory, and the processor are connected by using the bus system, thememory is configured to store an instruction, the processor isconfigured to execute the instruction stored in the memory to controlthe receiver to receive a signal and to control the transmitter to senda signal, and when the processor executes the instruction stored in thememory, the execution enables the processor to perform the methodaccording to the first aspect or any possible implementation of thefirst aspect.

According to a twelfth aspect, the present application provides aservice function forwarding node, where the service function forwardingnode includes a receiver, a transmitter, a memory, a processor, and abus system. The receiver, the transmitter, the memory, and the processorare connected by using the bus system, the memory is configured to storean instruction, the processor is configured to execute the instructionstored in the memory to control the receiver to receive a signal and tocontrol the transmitter to send a signal, and when the processorexecutes the instruction stored in the memory, the execution enables theprocessor to perform the method according to the second aspect or anypossible implementation of the second aspect.

According to a thirteenth aspect, the present application provides acontrol node, where the control node includes a receiver, a transmitter,a memory, a processor, and a bus system. The receiver, the transmitter,the memory, and the processor are connected by using the bus system, thememory is configured to store an instruction, the processor isconfigured to execute the instruction stored in the memory to controlthe receiver to receive a signal and to control the transmitter to senda signal, and when the processor executes the instruction stored in thememory, the execution enables the processor to perform the methodaccording to the third aspect or any possible implementation of thethird aspect.

According to a fourteenth aspect, the present application provides aservice function forwarding node, where the service function forwardingnode includes a receiver, a transmitter, a memory, a processor, and abus system. The receiver, the transmitter, the memory, and the processorare connected by using the bus system, the memory is configured to storean instruction, the processor is configured to execute the instructionstored in the memory to control the receiver to receive a signal and tocontrol the transmitter to send a signal, and when the processorexecutes the instruction stored in the memory, the execution enables theprocessor to perform the method according to the fourth aspect or anypossible implementation of the fourth aspect.

The present application provides the method, the apparatus, and thesystem for forwarding a packet in SFC, so that interaction between therouting and switching device and the controller is standardized, toimplement smooth interconnection of an SFC service between thecontroller and the routing and switching device.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentapplication more clearly, the following briefly describes theaccompanying drawings required for describing the embodiments or theprior art. Apparently, the accompanying drawings in the followingdescription show merely some embodiments of the present application, anda person of ordinary skill in the art may still derive other drawingsfrom these accompanying drawings without creative efforts.

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of the present application;

FIG. 2 is a schematic flowchart of a method for forwarding a packet inSFC according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a multiprotocol reachable network layerreachability information (MP_REACH_NLRI) attribute field encapsulatedbased on an encapsulation format supported by a Border Gateway Protocol(BGP) SFC synchronization address family according to an embodiment ofthe present application;

FIG. 4 is a schematic diagram of a type-length-value (TLV) field in anNLRI field according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a sub-TLV field in a BGP SFC attribute(Attribute) field according to an embodiment of the present application;

FIG. 6 is a schematic flowchart of a method for forwarding a packet inSFC according to another embodiment of the present application;

FIG. 7 is a schematic block diagram of a control node according to anembodiment of the present application;

FIG. 8 is a schematic block diagram of a service function forwardingnode according to an embodiment of the present application;

FIG. 9 is a schematic block diagram of a system for forwarding a packetin SFC according to an embodiment of the present application;

FIG. 10 is a schematic block diagram of a control node according toanother embodiment of the present application;

FIG. 11 is a schematic block diagram of a service function forwardingnode according to another embodiment of the present application;

FIG. 12 is a schematic block diagram of a system for forwarding a packetin SFC according to another embodiment of the present application;

FIG. 13 is another schematic block diagram of a control node accordingto an embodiment of the present application;

FIG. 14 is another schematic block diagram of a service functionforwarding node according to an embodiment of the present application;

FIG. 15 is another schematic block diagram of a control node accordingto another embodiment of the present application; and

FIG. 16 is another schematic block diagram of a service functionforwarding node according to another embodiment of the presentapplication.

DESCRIPTION OF EMBODIMENTS

The following describes the technical solutions in embodiments of thepresent application with reference to the accompanying drawings in theembodiments of the present application. Apparently, the describedembodiments are some but not all of the embodiments of the presentapplication. All other embodiments obtained by a person of ordinaryskill in the art based on the embodiments of the present applicationwithout creative efforts shall fall within the protection scope of thepresent application.

For ease of understanding and description of a method, an apparatus, anda system for forwarding a packet in SFC in the embodiments of thepresent application, an application scenario of the embodiments of thepresent application is first described with reference to FIG. 1.

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of the present application. As shown in FIG. 1, SFC 100includes a service classification node (or a service classifier (SC))110, service function forwarding nodes (or service function forwarders(SFF)), service function nodes (or service function (SF) processors), apost service (PS) node 140, and a control node (or a controller) 160.For example, the SFFs include an SFF 1 120 a and an SFF 2 120 b; and theSFs include an SF 1 130 a and an SF 2 130 b.

Herein, it should be noted that the SFC is a virtual Overlay network ofa basic underlying network (for example, an underlying IP network). TheSFC includes some nodes (for example, nodes having service processingand forwarding functions) in the basic underlying network. To bespecific, the nodes included in the SFC are not all physically anddirectly connected. For example, a network element node, such as arouter or a switch, may be connected between SFF nodes.

In other words, in addition to the service classification node, theservice function forwarding node, the service function node, and thepost service node that are enumerated above, the SFC further includes aplurality of routing and switching devices in a physical network inwhich the SFC is located. The service classification node, the servicefunction forwarding node, the service function node, the post servicenode, and the routing and switching devices that are enumerated aboveall may be referred to as network nodes. For ease of distinguishing, theservice classification node, the service function forwarding node, theservice function node, and the post service node that are in the SFC arecollectively referred to as SFC nodes. The plurality of routing andswitching devices in the physical network are configured to forward apacket from one SFC node to another SFC node. It should be understoodthat the SFC nodes enumerated above are merely described as examples,which should impose no limitation to the present application. The SFCnode may further include another node configured to implement an SFCfunction in an SFC network. For brevity, details are not describedherein.

It should also be understood that the SFC nodes enumerated above may beunderstood as functional modules, and are respectively configured toperform respective corresponding functions. Each SFC node may bedeployed separately or a plurality of SFC nodes may be deployed in acombined manner. A specific deployment manner of each SFC node is notlimited in the present application. For example, the SC and the SFF 1may be deployed in one physical device in a combined manner. Thephysical device has a traffic matching function of the SC and a serviceforwarding function of the SFF 1, or has an SC module and an SFF module.In the following, unless otherwise stated, it is considered that the SCand the SFF 1 are deployed in a combined manner, that is, the SFF 1deployed in a combined manner has functions of traffic matching andservice forwarding.

As shown in FIG. 1, when the packet reaches the SFF 1 120 a, the SFF 1120 a parses traffic characteristic information (for example, 5-tupleinformation) of traffic carried by the packet, filters the packet, anddirects, to a corresponding service function path (SFP), a packet thatmatches a filter criterion (or a match item) of the trafficcharacteristic information. The SFF 1 120 a, as a first service functionforwarding node that the packet enters, encapsulates the packet based onthe matched SFP. An encapsulated packet includes an SFC header, and theSFC header includes a service function path identifier (SPI) that isused to indicate the SFP that matches the packet. Then, the SFF 1 120 aforwards the encapsulated packet to a next SFC node. The SFF 1 120 aforwards the encapsulated packet to the SF 1 node 130 a based on theSFP, the SF 1 node 130 a returns the packet to the SFF 1 120 a afterprocessing the packet, the SFF 1 120 a continues to forward, based onthe SFP that matches the packet, the packet processed by the SF1 node130 a to the SFF 2 120 b, and so on, until the packet is transmitted tothe PS node 140 of the SFP of the packet.

The packet may be forwarded between SFC nodes, for example, between twoservice function forwarding nodes or between a service functionforwarding node and a service function node, by using a plurality ofrouting and switching devices. In other words, there may be a pluralityof channels between the two service function forwarding nodes or betweenthe service function forwarding node and the service function node, andthe plurality of channels are formed by different routing and switchingdevices together.

Referring to FIG. 1 again, the SFF 1 120 a may reach the SF 1 130 a byusing a routing and switching device (for example, a router (Router) 11150 a), or the SFF 1 120 a may reach the SF 1 130 a by using a router 21150 b and a router 22 150 c, or the SFF 1 120 a may reach the SF 1 130 aby using a router 31 150 d. In other words, the packet may reach the SF1 130 a from the SFF 1 120 a through three channels.

In this embodiment of the present application, to help to distinguishand understand, a link that connects two service function forwardingnodes is referred to as an SFP, and a link that is formed by routing andswitching devices connected between two service function forwardingnodes or between the service function forwarding node and the servicefunction node is referred to as a channel. It can be understood that achannel is a part of an SFP. One SFP may include different channels, orone SFP may correspond to a plurality of channels. This is notparticularly limited in the present application. For example, SFF 1 120a→Router 11 150 a→SF 1 130 a, SFF 1 120 a→Router 21 150 b→Router 22 150c→SF 1 130 a, and SFF 1 120 a→Router 31 150 d→SF 1 130 a shown in FIG. 1may be considered as three different channels that form a same SFP. Itshould be understood that a connection relationship between the SFP andthe channels shown in FIG. 1 is merely described as an example, whichshould impose no limitation to the present application. A connectionrelationship between each SFC node and routing and switching devices isnot limited to that shown in FIG. 1, and is not particularly limited inthe present application.

During an actual forwarding process, the service function forwardingnode may direct the packet to a next node by using next hop informationcorresponding to route prefix information. For example, a next hop nodeof the SFF 1 120 a shown in FIG. 1 may be the router 11 150 a, may bethe router 21 150 b, or may be the router 31 150 d. The packet isforwarded from the SFF 1 120 a to any one of the next hop nodes; therouter 11 150 a, the router 21 150 b, and the router 31 150 d, or thepacket passes through any one of the foregoing three channels, andfinally reaches a destination node (or a next SFC node), namely, SF 1130 a.

It should be noted that the route prefix information described hereinand forwarding prefix information described in the following may beroute prefix information used in the SFC, and are different fromconventional route prefix information (for example, IP route prefixinformation).

It should be understood that, in the SFC, each service functionforwarding node may be connected to at least one SFC node by usingdifferent routing and forwarding devices, and the at least one SFC nodemay be a service function node or may be a service function forwardingnode. In other words, each service function forwarding node may besimultaneously located in at least one SFP. When the packet enters thefirst service function forwarding node of the SFP, the packet needs tobe forwarded based on a forwarding entry corresponding to the SFP.

It can be learned from the foregoing that the SFC node transmits thepacket based on the SFP. In other words, the packet is transmitted basedon an SFC forwarding table. The SFC forwarding table is determined basedon network topology information of the SFC. Therefore, before forwardingthe packet, the control node (or the controller) needs to pre-configurea plurality of SFPs in the SFC based on related information of nodessuch as the SC, the SFF, the SF, and the PS in the SFC, to matchforwarding requirements of different packets. After being created, eachnew SFP is delivered to nodes (including SFF and SF nodes) in the SPF,to help the nodes and the control node to synchronize forwarding entryinformation.

It should be understood that an SFC service is deployed in an SDN. TheSDN includes a controller (which is an example of the control node) andan SDN routing and switching device (which is an example of the servicefunction forwarding node). The controller and the SDN routing andswitching device implement synchronization of the forwarding entry byusing a southbound interface protocol, for example, OpenFlow. Aftercreating a routing entry for the new SFP, the controller may calculate,based on a flow table format supported by OpenFlow, to generate a flowtable (which is an example of the forwarding table), and delivers theflow table to each service function forwarding node in a point-to-pointmanner. Each service function forwarding node forwards the packet basedon the received flow table. This service function forwarding node is anSDN-only routing and switching device that supports only an operationdefined by the OpenFlow specification, for example, an OpenFlow-onlyswitch.

In an existing SDN, this SDN-only routing and switching device isusually a virtual switch implemented by using a software-only forwardingtechnology, for example, an Open vSwitch (OVS). An OpenFlow-only switchimplemented by a hardware forwarding technology is limited by a chiptechnology and still requires a relatively long research and developmenttime. Therefore, a mainstream SDN routing and switching device is stillan SDN hybrid routing and switching device, for example, anOpenFlow-hybrid switch. This SDN hybrid routing and switching device isusually implemented based on hardware improvements of a conventionalrouting and switching device. However, the hardware improvements for theconventional routing and switching device that are made by vendors areprivate extensions, and the private extensions of the vendors are notunified. Consequently, interaction between the conventional routing andswitching device and the controller cannot be standardized, andinterconnection of an SFC service between the controller and the routingand switching device is difficult to implement.

Therefore, the present application provides an SFC-based packetforwarding method to standardize interaction between the routing andswitching device and the controller, and resolve a problem of difficultinterconnection between the controller and the routing and switchingdevice during synchronization of the forwarding entry.

The following describes in detail a method for forwarding a packet inSFC according to an embodiment of the present application with referenceto FIG. 2 to FIG. 6.

FIG. 2 is a schematic flowchart of a method 200 for forwarding a packetin SFC according to an embodiment of the present application. It shouldbe understood that FIG. 2 shows detailed communication steps oroperations of the method for forwarding a packet in the SFC, but thesesteps or operations are merely examples, and other operations orvariations of the operations in FIG. 2 may also be performed in thisembodiment of the present application. In addition, the steps in FIG. 2may be performed in an order different from that presented in FIG. 2,and it is possible that not all operations in FIG. 2 need to beperformed.

As shown in FIG. 2, the method 200 includes the following steps:

S210. A control node determines routing entry information of a servicefunction forwarding node in a service function path SFP in the SFC.

S220. The control node sends the routing entry information to theservice function forwarding node.

The control node may pre-configure at least one SFP based on adistribution status of network nodes in the SFC, to match packets thathave different traffic. In a same SFC, different SFPs can bedistinguished by service path identifiers SPIs. In other words, each SPIcorresponds to one SFP. In a same SFP, a location of each servicefunction forwarding node in the SFP may be indicated by using a serviceindex (SI), where the SI performs an SI−1 operation every time a packetpasses through one service function node.

Herein, it should be noted that one service function forwarding node maysimultaneously belong to at least one SFP. Because the SPIscorresponding to the SFPs are different, the service function forwardingnode may also correspondingly have different SPIs to distinguishdifferent SFPs. In other words, a specific SFP and a location of aservice function forwarding node in the SFP can be jointly indicated bythe SPI and the SI.

In this embodiment of the present application, the SPI and the SI may becollectively referred to as route prefix information. The routing entryinformation records a mapping relationship between route prefixinformation and next hop information, the route prefix information mayindicate a specific SFP, and determines a location, in the specific SFP,of a service function forwarding node in which a packet is currentlylocated, and the next hop information indicates an address of a next hopnode of the service function forwarding node. In other words, when apacket enters a service function forwarding node, the route prefixinformation may be used as a route to find an address of a correspondingnext hop node, thereby forwarding the packet to the next hop node. Itshould be noted that the next hop node described herein may be an SFCnode or a routing and switching device in a physical network. This isrelated to a node to which the service function forwarding node isdirectly connected. When the service function forwarding node (forexample, the SFF 1 shown in FIG. 1) is directly connected to a servicefunction node (for example, the SF 2 shown in FIG. 1) or a servicefunction forwarding node (for example, the SFF 2 shown in FIG. 1), thenext hop node of the service function forwarding node is an SFC node(for example, the service function node or the service functionforwarding node). When the service function forwarding node (forexample, the SFF 1 shown in FIG. 1) is directly connected to a routingand switching device (for example, the router shown in FIG. 1) in aphysical network, the next hop node of the service function forwardingnode is a routing and switching device.

For example, the at least one SFP may include a first SFP, and the firstSFP may include the service function forwarding node. As shown in FIG.1, it is assumed that SC→SFF 1→SF 1→SFF 1→SF 2→SFF 1→SFF 2→PS shown inFIG. 1 is the first SFP, and the SC and the SFF 1 are deployed on onedevice in a combined manner, then the SC or the SFF 1 is an ingress node(or a head node).

After determining the first SFP, the control node may send correspondingrouting entry information to each node. The control node determinesfirst routing entry information of a first service function forwardingnode in the first SFP, and sends the first routing entry information tothe first service function forwarding node.

It should be noted that routing entry information of each servicefunction forwarding node in the SFC is stored in the control node, andeach piece of routing entry information may correspond to one SFP. Inthe service function forwarding node included in each SFP, one SFP maycorrespond to one or more pieces of routing entry information. Allpieces of routing entry information of the service function forwardingnodes form a routing table. In other words, the routing entryinformation may be understood as a subset of the routing table.

It should also be noted that in this embodiment of the presentapplication, the SFP pre-configured by the control node is unrelated tocharacteristic information of traffic carried by the packet. The SFP maybe understood as one or more paths that are used to transmit packets andthat are pre-configured in the SFC. When entering a service functionforwarding node in the SFP, a packet may enter a next node of this pathby using a route of the service function forwarding node.

It should also be noted that the control node may pre-store routingentry information of each service function forwarding node in each SFPinto a locally stored routing information base (RIB) based on thepre-configured SFP. In other words, the control node may obtain routingentry information of any service function forwarding node of any SFP inthe SFC. To differ from a routing table that is stored in a servicefunction forwarding node described in the following, a routing tablestored in the control node is referred to as an SFC routing table, and arouting table stored in each service function forwarding node isdetermined based on the SFC routing table. The control node sendsrouting entry information to each service function forwarding node basedon the SFC routing table, and each service function forwarding nodeupdates the locally stored routing table based on the received routingentry information.

For ease of understanding and description, by using a specific processof forwarding a packet as an example, the following describes in detailthe routing entry information delivered by the control node to theservice function forwarding node with reference to FIG. 1 and Table 1.

It is assumed that a packet (referred to as a first packet for ease ofdescription) that enters the SFC is directed to the first SFP, namely,SC→SFF 1→SF 1→SFF 1→SF 2→SFF 1→SFF 2→PS shown in FIG. 1. The SC and theSFF 1 may be deployed as the SFF 1 in a combined manner, and the PS andthe SFF 2 may be deployed as the SFF 2 in a combined manner. For ease ofdescription, descriptions on the SC and the PS are omitted below.

For example, a SPI corresponding to the first SFP may be 10, and an SIof an ingress node (namely, the SFF 1) may be 255. To be specific, routeprefix information of the SFF 1 may be as follows: SPI=10 and SI=255.Routing entry information of the SFF 1 in the first SFP may be shown inTable 1.

TABLE 1 SPI SI Next hop information 10 255 10.1.1.1/31 10 25410.1.1.3/31 10 253  2.2.2.2/32

With reference to FIG. 1 and Table 1, it can be learned that in thefirst SFP, after the first packet enters the SFF 1, the route prefixinformation SPI=10 and SI=255 points to next hop information10.1.1.1/31. To be specific, the next hop points to the SF 1, and thefirst packet is forwarded to the SF 1 by the SFF 1. After beingprocessed by a service function of the SF 1, the first packet isreturned to the SFF 1, and an SI−1 operation is performed. In this case,route prefix information of the SFF 1 is SPI=10 and SI=254, and pointsto next hop information 10.1.1.3/31. To be specific, the next hop pointsto the SF 2, and the first packet is forwarded to the SF 2 by the SFF 1.After being processed by a service function of the SF 2, the firstpacket is returned to the SFF 1 again, and an SI−1 operation isperformed. In this case, route prefix information of the SFF 1 is SPI=10and SI=253, and points to next hop information 2.2.2.2/32. To bespecific, the next hop points to the SFF 2. Therefore, the first packetis forwarded to the next service function forwarding node SFF 2 by theSFF 1.

It should be noted that the route prefix information of the SFF 1 andthe corresponding next hop information that are listed in Table 1indicate a connection relationship between SFC nodes, and are forwardingentry information shown as an example when a control granularity is anSFC node, which should impose no limitation to the present application.Using FIG. 1 as an example, in an actual first packet forwardingprocess, the next hop information corresponding to the route prefixinformation: SPI=10 and SI=255, of the SFF 1 may be an address of therouter 11, or may be an address of the router 21, or may be an addressof the router 31. In other words, the route prefix information: SPI=10and SI=255, of the SFF 1 may correspond to three entries, each entryincludes a correspondence between the route prefix information and anaddress of a routing and switching device (for example, the router 11,the router 21, or the router 31 shown in FIG. 1). After being directedto the router 11, the router 21, or the router 31, the first packet maybe continuously forwarded based on the routing entry information of therouter 11, the router 21, or the router 31 until the first packet isforwarded to the SF 1.

Herein, for ease of description, an address of the SF 1 is denoted asthe next hop information corresponding to the route prefix information:SPI=10 and SI=255, of the SFF 1, which should impose no limitation tothe present application. Likewise, an address of the SF 2 is denoted asnext hop information corresponding to the route prefix information:SPI=10 and SI=254, of the SFF 1, and an address of the SFF 2 is denotedas next hop information corresponding to the route prefix information:SPI=10 and SI=253, of the SFF 1.

In this embodiment of the present application, the SFF 1 corresponds tothree pieces of route prefix information in the first SFP, and the threepieces of route prefix information have a same SPI (that is, correspondto a same SFP), but have different SIs, because every time the firstpacket passes through the SFF 1, a location of the SFF 1 in the firstSFP varies. Next hop information corresponding to the pieces of routeprefix information is also different. To be specific, next hop nodes towhich the packet is directed by the pieces of route prefix informationare also different. Mapping relationships between the three pieces ofroute prefix information and the three pieces of next hop informationform routing entry information of the SFF 1 in the first SFP.

After determining the first SFP, the control node may send the routingentry information of the SFF 1 to the SFF 1, so that the SFF 1 forwardsa packet based on the routing entry information.

It should be understood that the routing entry information shown inTable 1 is merely described as an example, which should impose nolimitation to the present application. The routing entry informationdelivered by the control node to the service function forwarding nodeincludes the SPI, the SI, and the next hop information that aredescribed in Table 1, but Table 1 is not necessarily a form ofexpression of the routing entry information, or the routing entryinformation may be delivered to the service function forwarding node byusing Table 1 or another form different from Table 1.

It should also be understood that the first SFP shown in FIG. 1 ismerely described as an example, which should impose no limitation to thepresent application. For example, a service function node may beconnected to the SFF 2, or a service function forwarding node may beconnected after the SFF 2. This is not particularly limited in thepresent application. When the service function node or the servicefunction forwarding node is connected to the SFF 2, the control node mayalso send routing entry information of the SFF 2 to the SFF 2, so thatthe SFF 2 forwards a packet based on the routing entry information.

It should also be understood that the control node may also determine asecond SFP in the SFC, and the second SFP may also include the foregoingservice function forwarding node. Therefore, after determining thesecond SFP, the control node may also send corresponding routing entryinformation to each node (including the service function forwardingnode) in the second SFP.

It should also be understood that the foregoing describes in detail therouting entry information in combination with the first packetforwarding process, but should impose no limitation to the routing entryinformation. The service function forwarding node may forward the packetbased on the routing entry information of the first SFP, or may forwardthe packet based on the routing entry information of the second SFP. Inother words, routing entry information of each SFP does not change dueto a path that the packet actually passes. Instead, an ingress node mayselect, based on attribute information of the packet, an SFP thatmatches the ingress node.

S230. The service function forwarding node stores the routing entryinformation into a routing table of the service function forwardingnode.

After receiving the routing entry information delivered by the controlnode, the service function forwarding node stores the routing entryinformation into a locally stored routing table. In other words, therouting table stores at least one piece of routing entry information,and the at least one piece of routing entry information may includerouting entry information of at least one SFP.

For example, the service function forwarding node is connected to boththe first SFP and the second SFP, and corresponding SPIs are a SPI 1 anda SPI 2 respectively; at least one piece of routing entry information ofthe first SFP is stored in the first service function forwarding node,and a SPI in corresponding route prefix information is the SPI 1; and atleast one piece of routing entry information of the second SFP is alsostored in the first service function forwarding node, and a SPI incorresponding route prefix information is the SPI 2.

Optionally, the method 200 further includes the following step:

S240. The service function forwarding node generates a forwarding tablebased on the routing table, and forwards a packet based on theforwarding table.

The service function node can calculate an optimal path from the locallystored routing table based on a current network status, generate theforwarding table, and forward the packet based on the forwarding table.As an example instead of a limitation, the forwarding table may be a FIBtable.

In other words, the service function forwarding node can store routingentry information of at least one SFP, but does not generate theforwarding table for routing entry information of each SFP. Theforwarding table is generated when one SFP is determined as an optimalpath. Optionally, the forwarding table generated by the service functionforwarding node may be stored locally, so as to be used again when apacket is forwarded based on a same SFP. The service function forwardingnode has a control plane and a forwarding plane. The control node sendsthe routing entry information to the control plane of the servicefunction forwarding node. The service function forwarding node storesthe routing entry information into the control plane, and calculates theoptimal path based on attribute information (for example, 5-tupleinformation) of a packet that enters the SFC, then generates theforwarding table based on information about the optimal path, anddelivers the forwarding table to the forwarding plane, so that theforwarding plane forwards the packet based on the forwarding table.

It should be noted that routing protocols such as BGP are protocolspecifications defined by the IETF bit by bit. These protocols havestrict standards and good interoperability, and can be directlyinterconnected to a plurality of vendors. Compared with an OpenFlow flowtable, the routing table and the forwarding table (for example, the FIBtable) are mature encoding formats at present, and interconnectionbetween the control node and the service function forwarding node isalso relatively easy.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers the routing entry information to the service functionforwarding node, the service function forwarding node generates theforwarding table, and interaction between the control node and theservice function forwarding node is standardized by using a matureprotocol, to implement smooth interconnection between the control nodeand the service function forwarding node. In addition, the servicefunction forwarding node can determine the optimal path based on thecurrent network status, and generates the forwarding table. In addition,the SPI and the SI are used as routes in a conventional routing andswitching device to direct the packet. To be specific, a routing policythat exists in an existing SDN device is used to flexibly process theroutes that exist in a “SPI and SI” manner. Compared with an existingconventional routing and switching device, the routing and switchingdevice in the present application is more convenient and flexible.

Optionally, the sending, by the control node, the routing entryinformation to the service function forwarding node includes:

generating, by the control node, a BGP update packet, where the BGPupdate packet carries the routing entry information; and

sending, by the control node, the BGP update packet to the servicefunction forwarding node.

In this embodiment of the present application, the routing entryinformation is carried by using a BGP packet. As an example instead of alimitation, the BGP packet may be the BGP update packet.

Optionally, the generating, by the control node, a BGP update packet,where the BGP update packet carries the routing entry informationincludes:

generating, by the control node, the BGP update packet, where the BGPupdate packet includes a multiprotocol reachable network layerreachability information (MP_REACH_NLRI) attribute field, and theMP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield. The SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, and the NLRI field includes atype-length-value (TLV) field. A type T field of the TLV field indicatesthat a type of the TLV field is an SFC routing entry synchronizationtype, and a value V field of the TLV field carries the SPI and the SI.The next hop information field carries the next hop information.

In this embodiment of the present application, the BGP SFCSynchronization address family can be newly added to the existing BGPaddress family, and the routing entry information is encapsulated basedon an encapsulation format supported by the newly added BGP SFCSynchronization address family. An encapsulation format of MP_REACH_NLRIof the newly added BGP SFC Synchronization address family is shown inFIG. 3.

FIG. 3 is a schematic diagram of an MP_REACH_NLRI attribute fieldencapsulated based on an encapsulation format supported by a BGP SFCSynchronization address family according to an embodiment of the presentapplication. The MP_REACH_NLRI may be understood as multiprotocolextension attribute information of network layer reachabilityinformation (NLRI), and includes three parts: an address familyinformation field, a next hop information field, and a network layerreachability information (NLRI) field.

The address family information field includes an address familyidentifier field (two bytes) and a subsequent address family identifierfield (one byte). The address family identifier (AFI) identifies anetwork layer protocol. For example, an AFI value of 1 indicates IPv4,and an AFI value of 2 indicates IPv6. The subsequent address familyidentifier (SAFI) identifies a type of a subsequent address family. Forexample, a SAFI value of 1 indicates unicast, a SAFI value of 2indicates multicast, and a SAFI value of 128 indicates a virtual privatenetwork (VPN). An AFI value of 1 and a SAFI value of 1 indicates that anIPv4 unicast route is carried in the NLRI field; an AFI value of 1 and aSAFI value of 128 indicates that a BGP-VPNv4 route is carried in theNLRI field; or an AFI value of 1 and a SAFI value of 4 indicates that aBGP label route is carried in the NLRI field.

In this embodiment of the present application, the BGP SFCSynchronization address family may be understood as a subsequent addressfamily extended from an IPv4 or IPv6 address family in the existing BGPprotocol. In other words, the AFI value may be 1 or 2. The SAFI valuemay be determined based on a standard formulated by the InternetEngineering Task Force (IETF).

The next hop information field includes a next hop address length field(one byte) and a next hop address field (variable length). The next hopaddress length field is used to identify a length of the next hopaddress field, and the length of the next hop address field isdetermined by the length indicated by the next hop address length field.

A one-byte reserved field exists between the next hop information fieldand the NLRI part.

The NLRI part includes an NLRI field, and the NLRI field furtherincludes a TLV field (variable length). FIG. 4 is a schematic diagram ofa TLV field in an NLRI field according to an embodiment of the presentapplication. A type T field indicates that a type of the TLV field is anSFC routing entry synchronization type, a length L field indicates alength of a V field, and a value V field carries a SPI and an SI. Inthis embodiment of the present application, a value 1 of the T field mayindicate an SFC forwarding entry synchronization (Forwarding EntrySynchronization) type; a value of the L field is 32 bits, namely, 4bytes; and the V field includes the SPI that is three bytes and the SIthat is one byte.

It should be understood that the Type 1 type enumerated herein is theSFC forwarding entry synchronization type, which is merely described asan example, and should impose no limitation to the present application.This embodiment of the present application does not exclude apossibility of indicating another type by using the Type 1 or indicatingthe SFC forwarding entry synchronization type by using another manner.In addition, a quantity of types of the NLRI Type is not particularlylimited in this embodiment of the present application either.

Further, the routing entry information further includes route attributeinformation, and the route attribute information includes at least oneof the following traffic distribution parameter types: weight, cost, andbandwidth.

In this embodiment of the present application, when receiving therouting entry information, the service function forwarding nodedistributes, based on the route attribute information carried in therouting entry information, forwarding traffic to a plurality of channelsthat reach a same target node. Therefore, the traffic may be distributedmore properly and flexibly in the SFC.

Optionally, the routing entry information further includes routeattribute information, and the route attribute information includes atleast one of the following traffic distribution parameter types: weight,cost, and bandwidth.

The BGP update packet further includes a BGP SFC attribute field, theBGP SFC Attribute field includes at least one sub-TLV field, and eachtraffic distribution parameter type corresponds to one of the at leastone sub-TLV field. Each sub-TLV field includes a T field (two bytes), anL field (two bytes), and a V field (determined by a value of the Lfield).

FIG. 5 is a schematic diagram of a sub-TLV field in a BGP SFC Attributefield according to an embodiment of the present application. A length ofa type T field is two bytes, a length of a length L field is two bytes,and a length of a value V field is determined by the length L field.Each sub-TLV is used to indicate a traffic distribution parameter. The Tfield indicates a traffic distribution parameter type. For example, avalue 1 of the T field may indicate weight; a value 2 of the T field mayindicate cost; or a value 3 of the T field may indicate bandwidth.

A piece of BGP SFC attribute information may be newly defined in a BGPupdate packet, and route attribute information is carried by at leastone sub TLV. As an example instead of a limitation, the route attributeinformation includes at least one of the following traffic distributionparameter types: weight, cost, and bandwidth. The T field indicates atraffic distribution parameter type. For example, a value 1 of the Tfield may indicate weight; a value 2 of the T field may indicate cost;or a value 3 of the T field may indicate bandwidth.

For example, when a value of a Sub-Type in a BGP SFC Attribute field ofrouting entry information delivered by a control node to a servicefunction forwarding node is 3, it indicates that the trafficdistribution parameter type is the bandwidth, that is, it indicates abandwidth value that can be used by an SFP indicated by the routingentry information. When a value of a Sub-Value is 200 M, it indicatesthat a bandwidth value that can be used by an SFP indicated by therouting entry information is 200 M. When traffic exceeds 200 M, thetraffic that exceeds 200 M is not allowed to be forwarded by using theSFP indicated by the routing entry information.

For another example, when a value of a Sub-Type in a BGP SFC Attributefield of routing entry information delivered by a control node to aservice function forwarding node is 2, it indicates that the trafficdistribution parameter type is the cost, that is, it indicates that whena plurality of entries are available, a primary entry may bepreferentially selected based on the cost, and if necessary, a secondaryentry may also be selected. In other words, when the trafficdistribution parameter type is the cost, the control node delivers, tothe service function forwarding node, at least two pieces of routingentry information that have a same SPI value and SI value.

Herein, it should be noted that as described above (refer to FIG. 1),when a control granularity is a routing and switching device connectedbetween SFC nodes, a plurality of pieces of routing entry informationthat are in the service function forwarding node, that are delivered bythe control node, and that have a same SPI value and SI value mayrespectively correspond to a plurality of different pieces of next hopinformation, may respectively correspond to different next hop routingand switching devices, or may correspond to different channels, andfinally reach a same SFC node (namely, a target node).

For example, Entry 1 is as follows:

SPI=10, SI=255, Next-Hop=11.1.1.1 BGP SFC Attribute: ... Sub-Type 2,Cost=5 ...

Entry 2 is as follows:

SPI=10, SI=255, Next-Hop=21.1.1.1 BGP SFC Attribute: ... Sub-Type 2,Cost=10 ...

It can be learned that Entry 1 and Entry 2 have the same SPI value andSI value, but correspond to different next hop information. For example,referring to FIG. 1, Entry 1 directs a packet to the router 11 by usingthe SFF 1, and Entry 2 directs a packet to the router 21 by using theSFF 1. In other words, there are two channels between the servicefunction forwarding node and the target node. In other words, two SFCnodes may be connected by using a plurality of routing and switchingdevices, and two channels formed by connecting the plurality of routingand switching devices are between the two SFC nodes. An cost value ofone channel is 5, and an cost value of the other channel is 10. Whenreceiving this routing entry information that carries the cost values,the service function forwarding node may use the channel having asmaller cost value to forward the packet. In other words, a smaller costvalue may indicate a higher priority. Alternatively, the channel with asmaller cost value may be used as a primary channel, and the channelwith a larger cost value may be used as a secondary channel.

For another example, when a value of a Sub-Type in a BGP SFC Attributefield of routing entry information delivered by a control node to aservice function forwarding node is 1, it indicates that the trafficdistribution parameter type is the weight, that is, it indicates thatwhen a plurality of entries perform load sharing, a proportion oftraffic carried by each entry may be calculated based on the weight. Inother words, when the traffic distribution parameter type is the weight,the control node delivers, to the service function forwarding node, atleast two pieces of routing entry information that have a same SPI valueand SI value. For example, Entry 3 is as follows:

SPI=10, SI=255, Next-Hop=11.1.1.1 BGP SFC Attribute: ... Sub-Type 1,Weight=20 ...

Entry 4 is as follows:

SPI=10, SI=255, Next-Hop=21.1.1.1 BGP SFC Attribute: ... Sub-Type 1,Weight=30 ...

Entry 5 is as follows:

SPI=10, SI=255, Next-Hop=31.1.1.1 BGP SFC Attribute: ... Sub-Type 1,Weight=50 ...

It can be learned that Entry 3, Entry 4, and Entry 5 have the same SPIvalue and SI value, but correspond to different next hop information.For example, referring to FIG. 1, Entry 3 directs a packet to the router11 by using the SFF 1, Entry 4 directs a packet to the router 21 byusing the SFF 1, and Entry 5 directs a packet to the router 31 by usingthe SFF 1. In other words, there are three channels between the servicefunction forwarding node and the target node. In other words, two SFCnodes may be connected by using a plurality of routing and switchingdevices, and two channels formed by connecting the plurality of routingand switching devices are between the two SFC nodes.

When receiving this routing entry information that carries weightvalues, the service function forwarding node can load and share trafficbased on a weight value of each channel. For example, in this example,when the channels corresponding to the three entries are used to sharethe traffic, a channel corresponding to Entry 3 shares 20%(20/(20+30+50)) of the traffic, a channel corresponding to Entry 4shares 30% (30/(20+30+50)) of the traffic, and a channel correspondingto Entry 5 shares 50% (50/(20+30+50)) of the traffic.

For another example, in the foregoing example, when Entry 5 is deleted,channels corresponding to the two remaining entries are used to sharetraffic forwarding, the channel corresponding to Entry 3 shares 40%(20/(20+30)) of the traffic, and the channel corresponding to Entry 4shares 60% (30/(20+30)) of the traffic. When there is only one availableentry, the weight value does not work.

It should be understood that the traffic distribution parameter typesthat are enumerated above are merely described as examples, which shouldimpose no limitation to the present application. A field for carryingthe route attribute information is not limited to the foregoing BGP SFCAttribute field, or another existing or newly added field may be usedfor carrying the route attribute information. This is not particularlylimited in the present application.

It should be understood that the above-enumerated method fordistributing the traffic based on the traffic distribution parameters ismerely described as an example, which should impose no limitation to thepresent application. For example, in this embodiment of the presentapplication, the control node may add a plurality of trafficdistribution parameter types to the routing entry information, and theservice function forwarding node may simultaneously distribute trafficbased on the plurality of traffic distribution parameter types.

It should also be understood that the above-enumerated method forcarrying the routing entry information by using the BGP update packetand the fields in the packet is merely described as an example, whichshould impose no limitation to the present application. The presentapplication does not exclude a possibility of carrying the foregoingrouting entry information by using another existing or newly addedfield.

Optionally, the storing, by the service function forwarding node, therouting entry information into a routing table of the service functionforwarding node in S230 includes:

searching, by the service function forwarding node based on the SPI andthe SI, the routing table of the service function forwarding node fortarget routing entry information having the same SPI and SI; and

updating, by the service function forwarding node, the target routingentry information based on the routing entry information when the targetrouting entry information is found; or

storing, by the service function forwarding node, the routing entryinformation when the target routing entry information is not found.

The service function forwarding node may use the SPI value, the SIvalue, and the next hop information that are in the routing entryinformation as key values for searching, and search a locally storedrouting table for the routing entry information that has the same SPIvalue, SI value, and next hop information (for ease of distinction anddescription, the routing entry information locally found by the servicefunction forwarding node is recorded as the target routing entryinformation).

The service function forwarding node may search for an entry of a Type 1type (namely, an SFC routing entry synchronization type) in a routingtable of a BGP SFC Synchronization address family.

If the service function forwarding node finds the target routing entryinformation in the locally stored routing table, the service functionforwarding node updates the target routing entry information based onthe route attribute information carried by the received routing entryinformation. If the service function forwarding node does not find thetarget routing entry information in the locally stored routing table,the service function forwarding node directly stores the receivedrouting entry information into the locally stored routing table, ornewly creates an entry of the Type 1 type and stores the routing entryinformation into the newly created entry.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the route attributeinformation is added in the routing entry information, so that theservice function forwarding node can distribute traffic more properlyand flexibly based on traffic distribution parameters.

It should be understood that the foregoing method for forwarding apacket in the SFC is a method for standardizing interaction between acontroller and a routing and switching device, which is provided for atransition phase in which a conventional routing and switching deviceand an SDN routing and switching device coexist in an existing SDN. Withdevelopment of the SDN, the SDN routing and switching device isgradually popular. When the SDN routing and switching device becomes awidely used routing and switching device, a routing entry informationsynchronization manner in the existing transition phase may be furtherimproved, so that a control plane is separated from a forwarding plane,the controller delivers forwarding entry information, and a routing andforwarding device does not need to calculate a forwarding table byitself.

Therefore, the present application provides another method forforwarding a packet in the SFC, so that the control plane can beseparated from the forwarding plane.

The following describes in detail a method for forwarding a packet inSFC according to another embodiment of the present application withreference to FIG. 6.

FIG. 6 is a schematic flowchart of a method 300 for forwarding a packetin SFC according to another embodiment of the present application. Itshould be understood that FIG. 6 shows detailed communication steps oroperations of the method for forwarding a packet in the SFC, but thesesteps or operations are merely examples, and other operations orvariations of the operations in FIG. 6 may also be performed in thisembodiment of the present application. In addition, the steps in FIG. 6may be performed in an order different from that presented in FIG. 6,and it is possible that not all operations in FIG. 6 need to beperformed.

As shown in FIG. 6, the method 300 includes the following steps:

S310. A control node determines forwarding entry information of aservice function forwarding node in a service function path SFP in theSFC.

The forwarding entry information records a mapping relationship betweenforwarding prefix information and next hop information. The forwardingprefix information includes a service path identifier SPI and a serviceindex SI, the SPI is used to identify the SFP, and the SI is used toidentify a location of the service function forwarding node in the SFP.The next hop information is used to indicate a next hop node of theservice function forwarding node in the SFP.

S320. The control node generates a Border Gateway Protocol (BGP) packet,where the BGP packet carries the forwarding entry information.

The control node may add the forwarding entry information to the BGPpacket. A specific method for carrying the forwarding entry informationby the BGP packet is similar to a specific method for carrying therouting entry information by the BGP update packet in the method 200.For brevity, details are not described herein again.

Optionally, that the control node generates a Border Gateway Protocol(BGP) packet, where the BGP packet carries the forwarding entryinformation in S320 includes:

generating, by the control node, the BGP packet, where the BGP packetincludes a multiprotocol reachable network layer reachabilityinformation (MP_REACH_NLRI) attribute field that is encapsulated basedon an encapsulation format supported by an SFC synchronization addressfamily, the MP_REACH_NLRI attribute field includes an NLRI field and anext hop information field, the NLRI field includes a type-length-value(TLV) field, a type T field of the TLV field indicates that a type ofthe TLV field is an SFC forwarding entry synchronization type, a value Vfield of the TLV field carries the SPI and the SI, and the next hopinformation field carries the next hop information.

Optionally, the forwarding entry information further includes forwardingattribute information, and the forwarding attribute information includesat least one of the following traffic distribution parameter types:weight, cost, and bandwidth.

The BGP packet further includes a BGP SFC attribute field, the BGP SFCAttribute field includes at least one sub-TLV field, and each trafficdistribution parameter type corresponds to one of the at least onesub-TLV field. Each sub-TLV field includes a T field, a length L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet. A specific carrying manner issimilar to that in the foregoing embodiment, and details are notdescribed herein again.

S330. The control node sends the BGP packet to the service functionforwarding node, where the forwarding entry information carried by theBGP packet is used to instruct the service function forwarding node toforward a packet.

S340. The service function forwarding node stores the forwarding entryinformation into a forwarding table of the service function forwardingnode.

The service function forwarding node stores the forwarding entryinformation, so as to directly forward, when a packet having sametraffic characteristic information is received subsequently, the packetbased on the forwarding entry information.

Optionally, the method 300 further includes the following step:

S350. The service function forwarding node forwards the packet based onthe forwarding entry information.

Optionally, in this embodiment of the present application, the BGPpacket may be a BGP update packet.

It should be understood that in this embodiment of the presentapplication, the service function forwarding node may store theforwarding table in a forwarding plane. A specific method for storingthe forwarding entry information by the service function forwarding nodeis similar to a specific method for storing the routing entryinformation by the service function forwarding node described above. Adifference is only that the routing entry information may be stored in acontrol plane of the service function forwarding node, and theforwarding entry information may be stored in the forwarding plane ofthe service function forwarding node. For brevity, detailed descriptionof the specific method for storing the forwarding entry information bythe service function forwarding node is omitted herein.

It should be noted that, different from the method 200, in thisembodiment of the present application, the control node may directlydetermine forwarding entry information of each service functionforwarding node based on a routing table, encapsulate the forwardingentry information by using the BGP packet, and deliver the forwardingentry information to the service function forwarding node. The servicefunction forwarding node may not store the routing table but only storethe forwarding table. In other words, the service function forwardingnode may not perform calculation but only forward the packet. Therefore,the control plane is separated from the forwarding plane, which helpsmanagement.

It should also be noted that content of information indicated by therouting entry information in the method 200 is similar to content ofinformation indicated by the forwarding entry information in the method300, and both may be used to indicate a SPI, an SI, and next hopinformation of a service function forwarding node, or a SPI, an SI, nexthop information, and route attribute information of a service functionnode. A difference is that in the method 200, the routing entryinformation may be stored in the routing table of the control plane ofthe service function forwarding node, and the service functionforwarding node needs to calculate by itself to generate an optimalpath, generates the forwarding table based on the optimal path, andperforms traffic matching and packet forwarding based on the forwardingtable; and in the method 300, the forwarding entry information may bedirectly stored in the forwarding plane of the service functionforwarding node, and is directly used to direct the service functionforwarding node to perform traffic matching and packet forwarding.

It should be understood that the “routing entry information” and the“forwarding entry information” are merely named separately fordistinguishing the foregoing two methods, which should impose nolimitation to the present application. The present application shouldnot be limited thereto. For example, in the method 300, the forwardingentry information may also be referred to as the routing entryinformation, or in the method 200, the routing entry information mayalso be referred to as the forwarding entry information.

Likewise, the “route attribute information” and the “forwardingattribute information” as well as the “route prefix information” and the“forwarding prefix information”, that are described above, are alsonamed separately for distinguishing the foregoing two methods, whichshould impose no limitation to the present application. The presentapplication should not be limited thereto.

It should also be understood that the above-enumerated method forcarrying the forwarding entry information by using the BGP packet andthe fields in the packet is merely described as an example, which shouldimpose no limitation to the present application. The present applicationdoes not exclude a possibility of carrying the foregoing forwardingentry information by using another existing or newly added field.

Therefore, according to the method for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers the forwarding entry information to the service functionforwarding node by using the BGP packet, and the service functionforwarding node can directly forward the packet based on the forwardingentry information. Interaction between the control node and the servicefunction forwarding node is standardized by using a mature protocol, toimplement smooth interconnection between the control node and theservice function forwarding node. In addition, the control plane isseparated from the forwarding plane, so that control planes offorwarding nodes are centralized on the controller, which helps toimplement a centralized service deployment strategy and implement acentralized management and maintenance strategy.

The foregoing describes in detail a method for forwarding a packet inthe SFC according to an embodiment of the present application withreference to FIG. 2 to FIG. 6. The following describes in detail anapparatus and a system for forwarding a packet in SFC according to anembodiment of the present application with reference to FIG. 7 to FIG.16.

FIG. 7 is a schematic block diagram of a control node 400 according toan embodiment of the present application. As shown in FIG. 7, thecontrol node 400 includes a determining module 410 and a sending module420.

The determining module 410 is configured to determine routing entryinformation of a service function forwarding node in a service functionpath SFP in service function chaining SFC, where the routing entryinformation records a mapping relationship between route prefixinformation and next hop information. The route prefix informationincludes a service path identifier SPI and a service index SI, the SPIis used to identify the SFP, and the SI is used to identify a locationof the service function forwarding node in the SFP. The next hopinformation is used to indicate a next hop node of the service functionforwarding node.

The sending module 420 is configured to send the routing entryinformation to the service function forwarding node, where the routingentry information is used by the service function forwarding node togenerate a forwarding table, and the forwarding table is used toinstruct the service function forwarding node to forward a packet.

Optionally, the control node 400 further includes a generating module,configured to generate a Border Gateway Protocol BGP update packet,where the BGP update packet carries the routing entry information.

The sending module 420 is configured to send the BGP update packet tothe service function forwarding node.

Optionally, the generating module is configured to generate the BGPupdate packet, where the BGP update packet includes a multiprotocolreachable network layer reachability information (MP_REACH_NLRI)attribute field, and the MP_REACH_NLRI attribute field includes asubsequent address family identifier (SAFI) field, an NLRI field, and anext hop information field. The SAFI field indicates that theMP_REACH_NLRI attribute field is encapsulated based on an encapsulationformat supported by an SFC synchronization address family, and the NLRIfield includes a type-length-value (TLV) field. A type T field of theTLV field indicates that a type of the TLV field is an SFC routing entrysynchronization type, and a value V field of the TLV field carries theSPI and the SI. The next hop information field carries the next hopinformation.

Optionally, the routing entry information further includes routeattribute information, and the route attribute information includes atleast one of the following traffic distribution parameter types: weight,cost, and bandwidth.

The BGP update packet further includes a BGP SFC attribute field, theBGP SFC Attribute field includes at least one sub-TLV field, and eachtraffic distribution parameter type corresponds to one of the at leastone sub-TLV field. Each sub-TLV field includes a T field, an L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

The control node 400 according to this embodiment of the presentapplication may correspond to a control node in a method for forwardinga packet in the SFC according to an embodiment of the presentapplication. In addition, the modules in the control node 400 and theforegoing other operations and/or functions are respectively used toimplement corresponding procedures of the method 200 in FIG. 2. Forbrevity, details are not described herein again.

Therefore, based on the control node in this embodiment of the presentapplication, the routing entry information is directly delivered to theservice function forwarding node, the service function forwarding nodegenerates the forwarding table, and interaction between the control nodeand the service function forwarding node is standardized by using amature protocol, to implement smooth interconnection between the controlnode and the service function forwarding node.

FIG. 8 is a schematic block diagram of a service function forwardingnode 500 according to an embodiment of the present application. As shownin FIG. 8, the service function forwarding node 500 includes a receivingmodule 510 and a processing module 520.

The receiving module 510 is configured to receive routing entryinformation sent by a control node, where the routing entry informationrecords a mapping relationship between route prefix information and nexthop information. The route prefix information includes a service pathidentifier (SPI) and a service index (SI), the SPI is used to identifyan SFP, and the SI is used to identify a location of the servicefunction forwarding node in the SFP. The next hop information is used toindicate a next hop node of the service function forwarding node.

The processing module 520 is configured to store the routing entryinformation into a routing table of the service function forwardingnode, so that the service function forwarding node generates aforwarding table based on the routing table, and forwards a packet basedon the forwarding table.

Optionally, the receiving module 510 is configured to receive a BorderGateway Protocol BGP update packet sent by the control node, where theBGP update packet carries the routing entry information.

Optionally, the BGP update packet includes a multiprotocol reachablenetwork layer reachability information (MP_REACH_NLRI) attribute field,and the MP_REACH_NLRI attribute field includes a subsequent addressfamily identifier (SAFI) field, an NLRI field, and a next hopinformation field. The SAFI field indicates that the MP_REACH_NLRIattribute field is encapsulated based on an encapsulation formatsupported by an SFC synchronization address family, and the NLRI fieldincludes a type-length-value (TLV) field. A type T field of the TLVfield indicates that a type of the TLV field is an SFC routing entrysynchronization type, and a value V field of the TLV field carries theSPI and the SI. The next hop information field carries the next hopinformation.

Optionally, the routing entry information further includes routeattribute information, and the route attribute information includes atleast one of the following traffic distribution parameter types: weight,cost, and bandwidth.

The BGP update packet further includes a BGP SFC attribute field, theBGP SFC Attribute field includes at least one sub-TLV field, and eachtraffic distribution parameter type corresponds to one of the at leastone sub-TLV field. Each sub-TLV field includes a T field, an L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

Optionally, the processing module 520 is configured to: search, based onthe SPI and the SI, the routing table of the service function forwardingnode for target routing entry information having the same SPI and SI;and

update the target routing entry information based on the routing entryinformation when the target routing entry information is found; or

store the routing entry information when the target routing entryinformation is not found.

The service function forwarding node 500 according to this embodiment ofthe present application may correspond to a service function forwardingnode in a method for forwarding a packet in the SFC according to anembodiment of the present application. In addition, the modules in theservice function forwarding node 500 and the foregoing other operationsand/or functions are respectively used to implement correspondingprocedures of the method 200 in FIG. 2. For brevity, details are notdescribed herein again.

Therefore, based on the service function forwarding node in thisembodiment of the present application, the routing entry informationdelivered by the control node is received, and the forwarding table isgenerated based on the routing entry information. Interaction betweenthe control node and the service function forwarding node isstandardized by using a mature protocol, to implement smoothinterconnection between the control node and the service functionforwarding node.

FIG. 9 is a schematic block diagram of a system 600 for forwarding apacket in SFC according to an embodiment of the present application. Asshown in FIG. 9, the system 600 for forwarding a packet includes thecontrol node 400 described in the foregoing embodiment and the servicefunction forwarding node 500 described in the foregoing embodiment.

It should be understood that modules in the system 600 for forwarding apacket and other operations and/or functions are respectively used toimplement corresponding procedures of the method 200 in FIG. 2. Forbrevity, details are not described herein again.

Therefore, based on the system for forwarding a packet in the SFC inthis embodiment of the present application, the control node directlydelivers routing entry information to the service function forwardingnode, and the service function forwarding node generates a forwardingtable based on the routing entry information. Interaction between thecontrol node and the service function forwarding node is standardized byusing a mature protocol, to implement smooth interconnection between thecontrol node and the service function forwarding node.

FIG. 10 is a schematic block diagram of a control node 700 according toanother embodiment of the present application. As shown in FIG. 10, thecontrol node 700 includes a determining module 710, a generating module720, and a sending module 730.

The determining module 710 is configured to determine forwarding entryinformation of a service function forwarding node in a service functionpath (SFP) in SFC, where the forwarding entry information records amapping relationship between forwarding prefix information and next hopinformation. The forwarding prefix information includes a service pathidentifier (SPI) and a service index (SI), the SPI is used to identifythe SFP, and the SI is used to identify a location of the servicefunction forwarding node in the SFP. The next hop information is used toindicate a next hop node of the service function forwarding node.

The generating module 720 is configured to generate a Border GatewayProtocol (BGP) packet, where the BGP packet carries the forwarding entryinformation.

The sending module 730 is configured to send the BGP packet to theservice function forwarding node, where the forwarding entry informationcarried by the BGP packet is used to instruct the service functionforwarding node to forward a packet.

Optionally, the generating module 720 is configured to generate the BGPpacket, where the BGP packet includes a multiprotocol reachable networklayer reachability information (MP_REACH_NLRI) attribute field, and theMP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield. The SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, and the NLRI field includes atype-length-value (TLV) field. A type T field of the TLV field indicatesthat a type of the TLV field is an SFC forwarding entry synchronizationtype, and a value V field of the TLV field carries the SPI and the SI.The next hop information field carries the next hop information.

Optionally, the forwarding entry information includes forwardingattribute information, and the forwarding attribute information includesat least one of the following traffic distribution parameter types:weight, cost, and bandwidth.

The BGP packet includes a BGP SFC attribute field, the BGP SFC Attributefield includes at least one sub-TLV field, and each traffic distributionparameter type corresponds to one of the at least one sub-TLV field.Each sub-TLV field includes a T field, a length L field, and a V field,where the T field indicates any one of the traffic distributionparameter types, and the V field indicates a parameter used todistribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

Optionally, the BGP packet is a BGP update packet.

The control node 700 according to this embodiment of the presentapplication may correspond to a control node in a method for forwardinga packet in the SFC according to an embodiment of the presentapplication. In addition, the modules in the control node 700 and theforegoing other operations and/or functions are respectively used toimplement corresponding procedures of the method 300 in FIG. 6. Forbrevity, details are not described herein again.

Therefore, based on the control node in this embodiment of the presentapplication, the forwarding entry information is directly delivered tothe service function forwarding node by using the BGP packet, and theservice function forwarding node can directly forward the packet basedon the forwarding entry information. Interaction between the controlnode and the service function forwarding node is standardized by using amature protocol, to implement smooth interconnection between the controlnode and the service function forwarding node. In addition, the controlplane is separated from the forwarding plane, which helps management.

FIG. 11 is a schematic block diagram of a service function forwardingnode 800 according to another embodiment of the present application. Asshown in FIG. 11, the service function forwarding node 800 includes areceiving module 810 and a processing module 820.

The receiving module 810 is configured to receive a Border GatewayProtocol (BGP) packet sent by a control node, where the BGP packetcarries forwarding entry information, and the forwarding entryinformation records a mapping relationship between SFC forwarding prefixinformation and next hop information. The SFC forwarding prefixinformation includes a service path identifier (SPI) and a service index(SI), the SPI is used to identify an SFP, and the SI is used to identifya location of the service function forwarding node in the SFP. The nexthop information is used to indicate a next hop node of the servicefunction forwarding node.

The processing module 820 is configured to store the forwarding entryinformation, so that the service function forwarding node 800 forwards apacket based on the forwarding entry information.

Optionally, the BGP packet includes a multiprotocol reachable networklayer reachability information (MP_REACH_NLRI) attribute field, and theMP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield. The SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, and the NLRI field includes atype-length-value (TLV) field. A type T field of the TLV field indicatesthat a type of the TLV field is an SFC forwarding entry synchronizationtype, and a value V field of the TLV field carries the SPI and the SI.The next hop information field carries the next hop information.

Optionally, the forwarding entry information includes forwardingattribute information, and the forwarding attribute information includesat least one of the following traffic distribution parameter types:weight, cost, and bandwidth.

The BGP packet includes a BGP SFC attribute Attribute field, the BGP SFCAttribute field includes at least one sub-TLV field, and each trafficdistribution parameter type corresponds to one of the at least onesub-TLV field. Each sub-TLV field includes a T field, a length L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

Optionally, the processing module 820 is configured to: search, based onthe SPI and the SI, a forwarding table of the service functionforwarding node for target forwarding entry information having the sameSPI and SI; and

update the target forwarding entry information based on the forwardingentry information when the target forwarding entry information is found;or

store the forwarding entry information when the target forwarding entryinformation is not found.

Optionally, the BGP packet is a BGP update packet.

The service function forwarding node 800 according to this embodiment ofthe present application may correspond to a service function forwardingnode in a method for forwarding a packet in the SFC according to anembodiment of the present application. In addition, the modules in theservice function forwarding node 800 and the foregoing other operationsand/or functions are respectively used to implement correspondingprocedures of the method 300 in FIG. 6. For brevity, details are notdescribed herein again.

Therefore, based on the service function forwarding node in thisembodiment of the present application, the BGP packet delivered by thecontrol node is received, and the packet is directly forwarded based onthe forwarding entry information. Interaction between the control nodeand the service function forwarding node is standardized by using amature protocol, to implement smooth interconnection between the controlnode and the service function forwarding node. In addition, the controlplane is separated from the forwarding plane, which helps management.

FIG. 12 is a schematic block diagram of a system 900 for forwarding apacket in SFC according to another embodiment of the presentapplication. As shown in FIG. 12, the system 900 for forwarding a packetincludes the control node 700 described in the foregoing embodiment andthe service function forwarding node 800 described in the foregoingembodiment.

It should be understood that modules in the system 900 for forwarding apacket and other operations and/or functions are respectively used toimplement corresponding procedures of the method 300 in FIG. 6. Forbrevity, details are not described herein again.

FIG. 13 is another schematic block diagram of a control node 10according to an embodiment of the present application. As shown in FIG.13, the control node 10 includes a receiver 11, a transmitter 12, aprocessor 13, a memory 14, and a bus system 15. The receiver 11, thetransmitter 12, the processor 13, and the memory 14 are connected byusing the bus system 15, the memory 14 is configured to store aninstruction, and the processor 13 is configured to execute theinstruction stored in the memory 14, to control the receiver 11 toreceive a signal and to control the transmitter 12 to send a signal.

The processor 13 is configured to determine routing entry information ofa service function forwarding node in a service function path SFP inservice function chaining (SFC), where the routing entry informationrecords a mapping relationship between route prefix information and nexthop information. The route prefix information includes a service pathidentifier (SPI) and a service index (SI), the SPI is used to identifythe SFP, and the SI is used to identify a location of the servicefunction forwarding node in the SFP. The next hop information is used toindicate a next hop node of the service function forwarding node.

The transmitter 12 is configured to send the routing entry informationto the service function forwarding node, where the routing entryinformation is used by the service function forwarding node to generatea forwarding table, and the forwarding table is used to instruct theservice function forwarding node to forward a packet.

It should be understood that in this embodiment of the presentapplication, the processor 13 may be a central processing unit (CPU).Alternatively, the processor 13 may be another general purposeprocessor, a digital signal processor (DSP), an application-specificintegrated circuit (ASIC), a field programmable gate array (FPGA) oranother programmable logic device, a discrete gate or a transistor logicdevice, a discrete hardware component, or the like. The general purposeprocessor may be a microprocessor. Alternatively, the processor may beany conventional processor or the like.

The memory 14 may include a read-only memory and a random access memory,and provide an instruction and data to the processor 13. A part of thememory 14 may further include a non-volatile random access memory. Forexample, the memory 14 may further store information about a devicetype.

In addition to a data bus, the bus system 15 may further include a powerbus, a control bus, a status signal bus, and the like. However, forclear description, various types of buses in the figure are marked asthe bus system 15.

During an implementation process, steps in the foregoing methods can beimplemented by using an integrated logical circuit of hardware in theprocessor 13, or by using an instruction in a form of software. Steps ofthe location method disclosed with reference to the embodiments of thepresent application may be directly performed and by using a hardwareprocessor, or may be performed and by using a combination of hardwareand software modules in the processor. The software module may belocated in a mature storage medium in the art, such as a random accessmemory, a flash memory, a read-only memory, a programmable read-onlymemory or an electrically erasable programmable memory, or a register.The storage medium is located in the memory 14, and the processor 13reads information in the memory 14 and the steps in the foregoingmethods in combination with hardware of the processor. To avoidrepetition, details are not described herein again.

Optionally, the processor 13 is further configured to generate a BorderGateway Protocol (BGP) update packet, where the BGP update packetcarries the routing entry information.

The transmitter 12 is configured to send the BGP update packet to theservice function forwarding node.

Optionally, the processor 13 is configured to generate the BGP updatepacket, where the BGP update packet includes a multiprotocol reachablenetwork layer reachability information (MP_REACH_NLRI) attribute field,and the MP_REACH_NLRI attribute field includes a subsequent addressfamily identifier (SAFI) field, an NLRI field, and a next hopinformation field. The SAFI field indicates that the MP_REACH_NLRIattribute field is encapsulated based on an encapsulation formatsupported by an SFC synchronization address family, and the NLRI fieldincludes a type-length-value (TLV) field. A type T field of the TLVfield indicates that a type of the TLV field is an SFC routing entrysynchronization type, and a value V field of the TLV field carries theSPI and the SI. The next hop information field carries the next hopinformation.

Optionally, the routing entry information further includes routeattribute information, and the route attribute information includes atleast one of the following traffic distribution parameter types: weight,cost, and bandwidth.

The BGP update packet further includes a BGP SFC attribute field, theBGP SFC Attribute field includes at least one sub-TLV field, and eachtraffic distribution parameter type corresponds to one of the at leastone sub-TLV field. Each sub-TLV field includes a T field, an L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

The control node 10 according to this embodiment of the presentapplication may correspond to a control node in a method for forwardinga packet in the SFC according to an embodiment of the presentapplication. In addition, the modules in the control node 10 and theforegoing other operations and/or functions are respectively used toimplement corresponding procedures of the method 200 in FIG. 2. Forbrevity, details are not described herein again.

Therefore, based on the control node in this embodiment of the presentapplication, the routing entry information is directly delivered to theservice function forwarding node, the service function forwarding nodegenerates the forwarding table, and interaction between the control nodeand the service function forwarding node is standardized by using amature protocol, to implement smooth interconnection between the controlnode and the service function forwarding node.

FIG. 14 is another schematic block diagram of a service functionforwarding node 20 according to an embodiment of the presentapplication. As shown in FIG. 14, the service function forwarding node20 includes a receiver 21, a transmitter 22, a processor 23, a memory24, and a bus system 25. The receiver 21, the transmitter 22, theprocessor 23, and the memory 24 are connected by using the bus system25, the memory 24 is configured to store an instruction, and theprocessor 23 is configured to execute the instruction stored in thememory 24, to control the receiver 21 to receive a signal and to controlthe transmitter 22 to send a signal.

The receiver 21 is configured to receive routing entry information sentby a control node, where the routing entry information records a mappingrelationship between route prefix information and next hop information.The route prefix information includes a service path identifier (SPI)and a service index (SI), the SPI is used to identify an SFP, and the SIis used to identify a location of the service function forwarding nodein the SFP. The next hop information is used to indicate a next hop nodeof the service function forwarding node.

The processor 23 is configured to generate a forwarding table based onthe routing entry information.

The transmitter 22 is configured to forward a packet based on theforwarding table.

Optionally, the receiver 21 is configured to receive a Border GatewayProtocol (BGP) update packet sent by the control node, where the BGPupdate packet carries the routing entry information.

Optionally, the BGP update packet includes a multiprotocol reachablenetwork layer reachability information (MP_REACH_NLRI) attribute field,and the MP_REACH_NLRI attribute field includes a subsequent addressfamily identifier (SAFI) field, an NLRI field, and a next hopinformation field. The SAFI field indicates that the MP_REACH_NLRIattribute field is encapsulated based on an encapsulation formatsupported by an SFC synchronization address family, and the NLRI fieldincludes a type-length-value (TLV) field. A type T field of the TLVfield indicates that a type of the TLV field is an SFC routing entrysynchronization type, and a value V field of the TLV field carries theSPI and the SI. The next hop information field carries the next hopinformation.

Optionally, the routing entry information further includes routeattribute information, and the route attribute information includes atleast one of the following traffic distribution parameter types: weight,cost, and bandwidth.

The BGP update packet further includes a BGP SFC attribute Attributefield, the BGP SFC Attribute field includes at least one sub-TLV field,and each traffic distribution parameter type corresponds to one of theat least one sub-TLV field. Each sub-TLV field includes a T field, an Lfield, and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

Optionally, the processor 23 is configured to: search, based on the SPIand the SI, the routing table of the service function forwarding nodefor target routing entry information having the same SPI and SI; and

update the target routing entry information based on the routing entryinformation when the target routing entry information is found; or

store the routing entry information when the target routing entryinformation is not found.

The service function forwarding node 20 according to this embodiment ofthe present application may correspond to a service function forwardingnode in a method for forwarding a packet in the SFC according to anembodiment of the present application. In addition, the modules in theservice function forwarding node 20 and the foregoing other operationsand/or functions are respectively used to implement correspondingprocedures of the method 200 in FIG. 2. For brevity, details are notdescribed herein again.

Therefore, based on the service function forwarding node in thisembodiment of the present application, the routing entry informationdelivered by the control node is received, and the forwarding table isgenerated based on the routing entry information. Interaction betweenthe control node and the service function forwarding node isstandardized by using a mature protocol, to implement smoothinterconnection between the control node and the service functionforwarding node.

FIG. 15 is another schematic block diagram of a control node 30according to another embodiment of the present application. As shown inFIG. 15, the control node 30 includes a receiver 31, a transmitter 32, aprocessor 33, a memory 34, and a bus system 35. The receiver 31, thetransmitter 32, the processor 33, and the memory 34 are connected byusing the bus system 35, the memory 34 is configured to store aninstruction, and the processor 33 is configured to execute theinstruction stored in the memory 34, to control the receiver 31 toreceive a signal and to control the transmitter 32 to send a signal.

The processor 33 is configured to determine forwarding entry informationof a service function forwarding node in a service function path (SFP)in SFC, where the forwarding entry information records a mappingrelationship between forwarding prefix information and next hopinformation. The forwarding prefix information includes a service pathidentifier (SPI) and a service index (SI), the SPI is used to identifythe SFP, and the SI is used to identify a location of the servicefunction forwarding node in the SFP. The next hop information is used toindicate a next hop node of the service function forwarding node.

The processor 33 is further configured to generate a Border GatewayProtocol (BGP) packet, where the BGP packet carries the forwarding entryinformation.

The transmitter 32 is configured to send the BGP packet to the servicefunction forwarding node, where the forwarding entry information carriedby the BGP packet is used to instruct the service function forwardingnode to forward a packet.

Optionally, the processor 33 is configured to generate the BGP packet,where the BGP packet includes a multiprotocol reachable network layerreachability information (MP_REACH_NLRI) attribute field, and theMP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield. The SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, and the NLRI field includes atype-length-value (TLV) field. A type T field of the TLV field indicatesthat a type of the TLV field is an SFC forwarding entry synchronizationtype, and a value V field of the TLV field carries the SPI and the SI.The next hop information field carries the next hop information.

Optionally, the forwarding entry information further includes forwardingattribute information, and the forwarding attribute information includesat least one of the following traffic distribution parameter types:weight, cost, and bandwidth.

The BGP packet further includes a BGP SFC attribute field, the BGP SFCAttribute field includes at least one sub-TLV field, and each trafficdistribution parameter type corresponds to one of the at least onesub-TLV field. Each sub-TLV field includes a T field, a length L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

Optionally, the BGP packet is a BGP update packet.

The control node 30 according to this embodiment of the presentapplication may correspond to a control node in a method for forwardinga packet in the SFC according to an embodiment of the presentapplication. In addition, the modules in the control node 30 and theforegoing other operations and/or functions are respectively used toimplement corresponding procedures of the method 300 in FIG. 6. Forbrevity, details are not described herein again.

Therefore, based on the control node in this embodiment of the presentapplication, the forwarding entry information is directly delivered tothe service function forwarding node by using the BGP packet, and theservice function forwarding node can directly forward the packet basedon the forwarding entry information. Interaction between the controlnode and the service function forwarding node is standardized by using amature protocol, to implement smooth interconnection between the controlnode and the service function forwarding node. In addition, the controlplane is separated from the forwarding plane, which helps management.

FIG. 16 is another schematic block diagram of a service functionforwarding node 40 according to another embodiment of the presentapplication. As shown in FIG. 16, the service function forwarding node40 includes a receiver 41, a transmitter 42, a processor 43, a memory44, and a bus system 45. The receiver 41, the transmitter 42, theprocessor 43, and the memory 44 are connected by using the bus system45, the memory 44 is configured to store an instruction, and theprocessor 43 is configured to execute the instruction stored in thememory 44, to control the receiver 41 to receive a signal and to controlthe transmitter 42 to send a signal.

The receiver 41 is configured to receive a Border Gateway Protocol (BGP)packet sent by a control node, where the BGP packet carries forwardingentry information, and the forwarding entry information records amapping relationship between SFC forwarding prefix information and nexthop information. The SFC forwarding prefix information includes aservice path identifier (SPI) and a service index (SI), the SPI is usedto identify an SFP, and the SI is used to identify a location of theservice function forwarding node in the SFP. The next hop information isused to indicate a next hop node of the service function forwardingnode.

The transmitter 42 is configured to forward a packet based on theforwarding entry information.

Optionally, the BGP packet includes a multiprotocol reachable networklayer reachability information (MP_REACH_NLRI) attribute field, and theMP_REACH_NLRI attribute field includes a subsequent address familyidentifier (SAFI) field, an NLRI field, and a next hop informationfield. The SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, and the NLRI field includes atype-length-value (TLV) field. A type T field of the TLV field indicatesthat a type of the TLV field is an SFC forwarding entry synchronizationtype, and a value V field of the TLV field carries the SPI and the SI.The next hop information field carries the next hop information.

Optionally, the forwarding entry information further includes forwardingattribute information, and the forwarding attribute information includesat least one of the following traffic distribution parameter types:weight, cost, and bandwidth.

The BGP packet further includes a BGP SFC attribute field, the BGP SFCAttribute field includes at least one sub-TLV field, and each trafficdistribution parameter type corresponds to one of the at least onesub-TLV field. Each sub-TLV field includes a T field, a length L field,and a V field, where the T field indicates any one of the trafficdistribution parameter types, and the V field indicates a parameter usedto distribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.

Optionally, the processor 43 is configured to: search, based on the SPIand the SI, a forwarding table of the service function forwarding nodefor target forwarding entry information having the same SPI and SI; and

update the target forwarding entry information based on the forwardingentry information when the target forwarding entry information is found;or

store the forwarding entry information when the target forwarding entryinformation is not found.

Optionally, the BGP packet is a BGP update packet.

The service function forwarding node 40 according to this embodiment ofthe present application may correspond to a service function forwardingnode in a method for forwarding a packet in the SFC according to anembodiment of the present application. In addition, the modules in theservice function forwarding node 40 and the foregoing other operationsand/or functions are respectively used to implement correspondingprocedures of the method 300 in FIG. 6. For brevity, details are notdescribed herein again.

Therefore, based on the service function forwarding node in thisembodiment of the present application, the BGP packet delivered by thecontrol node is received, and the packet is directly forwarded based onthe forwarding entry information. Interaction between the control nodeand the service function forwarding node is standardized by using amature protocol, to implement smooth interconnection between the controlnode and the service function forwarding node. In addition, the controlplane is separated from the forwarding plane, which helps management.

It should be understood that the term “and/or” in the specificationdescribes only an association relationship for describing associatedobjects and represents that three relationships may exist. For example,A and/or B may represent the following three cases: Only A exists, bothA and B exist, and only B exists. In addition, the character “/” in thespecification generally indicates an “or” relationship between theassociated objects.

It should be understood that sequence numbers of the foregoing processesdo not mean execution sequences in the embodiments of the presentapplication. The execution sequences of the processes should bedetermined based on functions and internal logic of the processes, andshould not be construed as any limitation on the implementationprocesses of the embodiments of the present application.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thespecification, units and algorithm steps may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of the present application.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, refer to acorresponding process in the foregoing method embodiments, and detailsare not described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in another manner. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division during actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented electrically, mechanically, or in other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentapplication may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit.

When the functions are implemented in the form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer readable storage medium. Based on such anunderstanding, the technical solutions of the present applicationessentially, or the part contributing to the prior art, or some of thetechnical solutions may be implemented in a form of a software product.The computer software product is stored in a storage medium, andincludes several instructions for instructing a computer device (whichmay be a personal computer, a server, or a network device) to performall or some of the steps of the methods described in the embodiments ofthe present application. The foregoing storage medium includes: anymedium that can store program code, such as a USB flash drive, aremovable hard disk, a read-only memory (ROM), a random access memory(RAM), a magnetic disk, or an optical disc.

The foregoing descriptions are merely specific implementations of thepresent application, but are not intended to limit the protection scopeof the present application. Any variation or replacement readily figuredout by a person skilled in the art within the technical scope disclosedin the present application shall fall within the protection scope of thepresent application. Therefore, the protection scope of the presentapplication shall be subject to the protection scope of the claims.

What is claimed is:
 1. A method, comprising: determining, by a controlnode, routing entry information of a service function forwarding node ina service function path (SFP) in the service function chaining (SFC),wherein the routing entry information records a mapping relationshipbetween route prefix information and next hop information, the routeprefix information comprises a service path identifier (SPI) and aservice index (SI), the SPI is used to identify the SFP, the SI is usedto identify a location of the service function forwarding node in theSFP, and the next hop information is used to indicate a next hop node ofthe service function forwarding node; and sending, by the control node,the routing entry information to the service function forwarding node,wherein the routing entry information is used by the service functionforwarding node to generate a forwarding table, and the forwarding tableis used to instruct the service function forwarding node to forward apacket.
 2. The method according to claim 1, wherein the sending, by thecontrol node, the routing entry information to the service functionforwarding node comprises: generating, by the control node, a BorderGateway Protocol (BGP) update packet, wherein the BGP update packetcarries the routing entry information; and sending, by the control node,the BGP update packet to the service function forwarding node.
 3. Themethod according to claim 2, wherein the generating, by the controlnode, a BGP update packet, wherein the BGP update packet carries therouting entry information comprises: generating, by the control node,the BGP update packet, wherein the BGP update packet comprises amultiprotocol reachable network layer reachability information(MP_REACH_NLRI) attribute field, the MP_REACH_NLRI attribute fieldcomprises a subsequent address family identifier (SAFI) field, a networklayer reachability information (NLRI) field, and a next hop informationfield, the SAFI field indicates that the MP_REACH_NLRI attribute fieldis encapsulated based on an encapsulation format supported by an SFCsynchronization address family, the NLRI field comprises atype-length-value (TLV) field, a type T field of the TLV field indicatesthat a type of the TLV field is an SFC routing entry synchronizationtype, a value V field of the TLV field carries the SPI and the SI, andthe next hop information field carries the next hop information.
 4. Themethod according to claim 3, wherein the routing entry informationfurther comprises route attribute information, and the route attributeinformation comprises at least one of the following traffic distributionparameter types: weight, cost, and bandwidth, wherein the BGP updatepacket further comprises a BGP SFC attribute field, the BGP SFCattribute field comprises at least one sub-TLV field, each trafficdistribution parameter type corresponds to one of the at least onesub-TLV field, each sub-TLV field comprises a T field, an L field, and aV field, the T field indicates any one of the traffic distributionparameter types, and the V field indicates a parameter used todistribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.
 5. A method, comprising: receiving,by a service function forwarding node, routing entry information sent bya control node, wherein the routing entry information records a mappingrelationship between route prefix information and next hop information,the route prefix information comprises a service path identifier (SPI)and a service index (SI), the SPI is used to identify an SFP, the SI isused to identify a location of the service function forwarding node inthe SFP, and the next hop information is used to indicate a next hopnode of the service function forwarding node; and storing, by theservice function forwarding node, the routing entry information into arouting table of the service function forwarding node, so that theservice function forwarding node generates a forwarding table based onthe routing table, and forwards a packet based on the forwarding table.6. The method according to claim 5, wherein the receiving, by a servicefunction forwarding node, routing entry information sent by a controlnode comprises: receiving, by the service function forwarding node, aBorder Gateway Protocol (BGP) update packet sent by the control node,wherein the BGP update packet carries the routing entry information. 7.The method according to claim 6, wherein the BGP update packet comprisesa multiprotocol reachable network layer reachability information(MP_REACH_NLRI) attribute field, the MP_REACH_NLRI attribute fieldcomprises a subsequent address family identifier (SAFI) field, an NLRIfield, and a next hop information field, the SAFI field indicates thatthe MP_REACH_NLRI attribute field is encapsulated based on anencapsulation format supported by an SFC synchronization address family,the NLRI field comprises a type-length-value (TLV) field, a type T fieldof the TLV field indicates that a type of the TLV field is an SFCrouting entry synchronization type, a value V field of the TLV fieldcarries the SPI and the SI, and the next hop information field carriesthe next hop information.
 8. The method according to claim 7, whereinthe routing entry information further comprises route attributeinformation, and the route attribute information comprises at least oneof the following traffic distribution parameter types: weight, cost, andbandwidth, wherein the BGP update packet further comprises a BGP SFCattribute field, the BGP SFC attribute field comprises at least onesub-TLV field, each traffic distribution parameter type corresponds toone of the at least one sub-TLV field, each sub-TLV field comprises a Tfield, an L field, and a V field, the T field indicates any one of thetraffic distribution parameter types, and the V field indicates aparameter used to distribute, based on a corresponding trafficdistribution parameter type, traffic carried by the packet.
 9. A controlnode, comprising: a processor and a memory coupled to the processor,wherein the processor is configured to: determine routing entryinformation of a service function forwarding node in a service functionpath (SFP) in service function chaining (SFC), wherein the routing entryinformation records a mapping relationship between route prefixinformation and next hop information, the route prefix informationcomprises a service path identifier (SPI) and a service index (SI), theSPI is used to identify the SFP, the SI is used to identify a locationof the service function forwarding node in the SFP, and the next hopinformation is used to indicate a next hop node of the service functionforwarding node; and send the routing entry information to the servicefunction forwarding node, wherein the routing entry information is usedby the service function forwarding node to generate a forwarding table,and the forwarding table is used to instruct the service functionforwarding node to forward a packet.
 10. The control node according toclaim 9, wherein the processor is configured to generate a BorderGateway Protocol (BGP) update packet, wherein the BGP update packetcarries the routing entry information; and send the BGP update packet tothe service function forwarding node.
 11. The control node according toclaim 10, wherein the BGP update packet comprises a multiprotocolreachable network layer reachability information (MP_REACH_NLRI)attribute field, the MP_REACH_NLRI attribute field comprises asubsequent address family identifier (SAFI) field, a network layerreachability information (NLRI) field, and a next hop information field,the SAFI field indicates that the MP_REACH_NLRI attribute field isencapsulated based on an encapsulation format supported by an SFCsynchronization address family, the NLRI field comprises atype-length-value (TLV) field, a type T field of the TLV field indicatesthat a type of the TLV field is an SFC routing entry synchronizationtype, a value V field of the TLV field carries the SPI and the SI, andthe next hop information field carries the next hop information.
 12. Thecontrol node according to claim 11, wherein the routing entryinformation further comprises route attribute information, and the routeattribute information comprises at least one of the following trafficdistribution parameter types: weight, cost, and bandwidth, wherein theBGP update packet further comprises a BGP SFC attribute field, the BGPSFC attribute field comprises at least one sub-TLV field, each trafficdistribution parameter type corresponds to one of the at least onesub-TLV field, each sub-TLV field comprises a T field, an L field, and aV field, the T field indicates any one of the traffic distributionparameter types, and the V field indicates a parameter used todistribute, based on a corresponding traffic distribution parametertype, traffic carried by the packet.
 13. A service function forwardingnode, comprising: a processor and a memory coupled to the processor,wherein the processor is configured to: receive routing entryinformation sent by a control node, wherein the routing entryinformation records a mapping relationship between route prefixinformation and next hop information, the route prefix informationcomprises a service path identifier (SPI) and a service index (SI), theSPI is used to identify an SFP, the SI is used to identify a location ofthe service function forwarding node in the SFP, and the next hopinformation is used to indicate a next hop node of the service functionforwarding node; and store the routing entry information into a routingtable of the service function forwarding node, so that the servicefunction forwarding node generates a forwarding table based on therouting table, and forwards a packet based on the forwarding table. 14.The service function forwarding node according to claim 13, wherein theprocessor is configured to receive a Border Gateway Protocol (BGP)update packet sent by the control node, wherein the BGP update packetcarries the routing entry information.
 15. The service functionforwarding node according to claim 14, wherein the BGP update packetcomprises a multiprotocol reachable network layer reachabilityinformation (MP_REACH_NLRI) attribute field, the MP_REACH_NLRI attributefield comprises a subsequent address family identifier (SAFI) field, anetwork layer reachability information (NLRI) field, and a next hopinformation field, the SAFI field indicates that the MP_REACH_NLRIattribute field is encapsulated based on an encapsulation formatsupported by an SFC synchronization address family, the NLRI fieldcomprises a type-length-value (TLV) field, a type T field of the TLVfield indicates that a type of the TLV field is an SFC routing entrysynchronization type, a value V field of the TLV field carries the SPIand the SI, and the next hop information field carries the next hopinformation.
 16. The service function forwarding node according to claim15, wherein the routing entry information further comprises routeattribute information, and the route attribute information comprises atleast one of the following traffic distribution parameter types: weight,cost, and bandwidth, wherein the BGP update packet further comprises aBGP SFC attribute field, the BGP SFC attribute field comprises at leastone sub-TLV field, each traffic distribution parameter type correspondsto one of the at least one sub-TLV field, each sub-TLV field comprises aT field, an L field, and a V field, the T field indicates any one of thetraffic distribution parameter types, and the V field indicates aparameter used to distribute, based on a corresponding trafficdistribution parameter type, traffic carried by the packet.